But what can a cyber criminal really do with a stolen credit card number?

For many, gaining credit card numbers is about more than simply making fraudulent purchases — although they do that as well, cyber-security expert Joseph Steinberg tells CNBC Make It. Credit card numbers can be converted into cash by buying up gift cards and purchasing easily sellable items to resell through online marketplaces such as eBay, Steinberg says.

Then there are the criminals who are interested in the big hauls. In many instances, the fraudster is actually selling your credit card number to other cyber criminals. The data from a single credit card can be sold for more than $45, data security provider Symantec reports. Let’s say you have a trove of credit card data, such as the 2018 Marriott data breachwhich compromised, among other pieces of data, credit and debit card payment information for 383 million people. That’s equivalent to billions of dollars in potential profits.

It’s not just through data breaches that cyber thieves can steal credit card information. Criminals are using a strategy called “formjacking,”where they use malicious code to steal your credit card details and other information during the checkout process on online retail sites. This type of fraud is on the rise, with reported attacks affecting major sites such as Ticketmaster and British Airways, Symantec reports.